seperate solar charge control or diversion?

[cardamon]

I have a 1 KW wind turbine hooked up to two L-16's.  Charge control is done with diversion.  I also have 240 watts of solar (2 120 watt, 12 volt).  I am curious what others' opinions are on how I should hook up the solar to the system.  Here are my thoughts:

1. Hook them directly to the batteries (the diversion controllers are big enough to handle both the wind and PV)  Advantage, cheap and simple.  Disadvantage, no mppt, leakage at night.  Could use diodes but then I get the loss.
   
2.  Buy a mppt controller.  Advantage, MPPT, prevents reverse current at night.  Disadvantage, cost.  I could buy another 120 watt panel for the cost of a mx-60 or similar and get 50% more output.
   
   

Thanks for any imput/ideas.

[electronbaby]

The system will work fine with both the wind and PV being regulated by the ONE diversion load controller. You just have to make sure the diversion load is sized for your max dump current. You MUST use blocking diodes on both sources. This is probably not an issue if you already have an external rectifier for the wind. Just make sure you use a blocking diode on the PV. This type of setup is not commonly done, but it will work fine. It is usually good to have two seperate controllers because this adds redundancy to the system and spreads out the failure points, so to speak. It is also nice to have versatility in the programming of the more expensive MPPT/diversion load controllers. You also will gain some efficiency at higher voltages with the MPPT controllers.

[cardamon]

I am wondering if PV blocking diodes are always good.  you would have to weigh the reverse flow at night against the voltage drop from the diodes during the day.  perhaps the theory is that, if your panels are not real hot and you are not using mppt, than the extra voltage overhead that the panels put out is not utilized anyway?  My panels draw 30 ma at night, which totals about .4 amp hours/day lost.  With blocking diodes what do I loose?  Well that a bit tough to figure out since I am not using MPPT, but if I was I could see loosing a lot more than that. Does a typical controller use diodes, or does it disconnect the pv from the batts when the voltage drops to worthless?

[tecker]

Set up two separate battery banks dumping from the dominant bank to the bank that's usually the one not in use . Using multiple banks provides a problem solving circuit that handles most problems .A few connections and these very different charges work at greatest efficiency .  A good for instance is lighting you might take over daily lighting with the solar and a battery bank and  Wind follows radical swings almost to a proportional that can at times take over the load from  heavy hitters in the house etc .     Batteries like to be either charged or discharged If you can't take over the load the bank is under the dipole in the battery is not established and it's just resistance to the charger .

[DamonHD]

You may damage the solar cells (with hotspots) if you allow reverse current to flow AFAIK.

Rgds

Damon

[ghurd]

I would go with #1.

The panels are designed to have enough voltage so the blocking diode voltage drop doesn't really effect the amps into the battery.

A 3rd PV would make more power per day than MPPT.

G-

[electronbaby]

charge controllers do the disconnecting with FET's. They are never really disconnected 100% (but close to it). They sense the sun coming up the following day and begin to work again. I would add blocking diodes for protection from the wind turbine. Also from reverse current in case you hook something up backwards. We are not talking about "bypass diodes", these are already "inside" your modules. Blocking diodes are cheap insurance for not discharging through your sources.

[cardamon]

thanks everyone for the comment.  I think ill direct connect for now, or maybe use a basic open circuiting type controller for the pv and set it above the diversion setpoints so I cn still utilize any extra power.  Ill let you know how it works out.

[shay]

I don't use reverse current diode blocking and I noticed one of my panels had a discoloration under the glass and a jumper wire had burnt on the outside (can be wired for 12 or 24volts). I'm wondering if a concentration of reverse current at night could do this? There is 200 amps at 12 vdc in bright sunlight and I see a max of 1 amp reverse current at night. This particular panel seems to have lower output and I'm thinking of removing it from the array. The outside burnt wire may be a 'confuser' but then I wouldn't know what caused it....maybe a shorted wire on the windpower mill that fried 200 feet away?  

[shay]

By splitting up the battery bank it enables quicker equalization of each individual bank. Not doing this routinely, leads to reduced life due to sulfation. There's two school of thought on desulfation- low current floatation charging and high frequency pulse desulfation.  

[shay]

For many years the system here at Morus Springs has run without diodes or controller. Some of the panels in the array have no bypass diodes and there is no reverse current diode. As mentioned (by me above) there may have been a problem but even with this unresolved I see over 200 amps at 12 vdc coming in and not more than an amp or two going out at night. Because of the mass of the system it is "balanced". MPPT controllers are becoming very efficient (97% claimed) so a 20-40% increase in power is possible and as I'm shifting from 12 to 24 there will be even more. I add batteries for 'balance' not forgetting that monthly equalization and spot desulfation of older batteries are all part of the equation. There are also two 1500 watt(ac) space heaters available if any consumption is needed:-)